Topic: Does anyone else's jeep backfire?

[Rio_Grande]

My 97 is finally back on the road and running at speed.

I noticed today while running around if I step aggressively on the gas it will backfire through the exhaust. It isint all the way out the back but more like under the passengers feet.

I hadn't driven this jeep at speed for several. Years and was disappointed at its gutlessness. I think I am going to pull the 34's and find a set of 31's to put on. It. Might look funny but I want to drive it.

[Tr00b]

Oxygen sensor to get rid of the backfire. Will get rid of some gutlessness stumbling and hesititations. Clean your intake air temp sensor as well. If your exhaust manifold is cracked, replace it...

34's? holy smokes. I have 31's and have to get out and push up hills... You must have to Fintstone that bish.

[dwtaylorpdx]

All three times my YJ did this the Cat, had gone or went bad. +1 on the O2,, Baxters, Oreillys have pretty good prices on them.

It also happens if the fuel filter starts to plug up, especially if the fuel level get low..

Dave

[grumpygy]

Mine only does it between shifts if I'm Pushing it hard. Say at least 4000 rpm.  Think its the Inj's dumping fuel as I let off to shift then get back on it..

[Rio_Grande]

Thanks for the repllys. I will warm it up and look at the numbers on the o2 sensors. What should they read?

Grumpy, that is when mine is doing it. If I get on it and then let off or shove the clutch in, pop pop pop.

It is pretty gutless on the road with 43 inch tires and 4.11 gears. I am not sure I ran it on the road much after I put the 34s on. The jeep was pretty much a trailer queen at the end. Trying to reverse that now. I want to be able to drive it on the road, to and from work and maybe the trail head.  We got too into offloading and building it bigger and gave up driving it on the road.

It had a cracked manifold, broken bolt in the exhaust. I fixed all that but have heard it reeks havoc on the o2 sensors. I will unplug the front one see if anything changes.

I am not convinced my injectors are not leaking. I just haven't ordered a set yet.

[Jeffy]

Thanks for the repllys. I will warm it up and look at the numbers on the o2 sensors. What should they read?

Grumpy, that is when mine is doing it. If I get on it and then let off or shove the clutch in, pop pop pop.

It is pretty gutless on the road with 43 inch tires and 4.11 gears. I am not sure I ran it on the road much after I put the 34s on. The jeep was pretty much a trailer queen at the end. Trying to reverse that now. I want to be able to drive it on the road, to and from work and maybe the trail head.  We got too into offloading and building it bigger and gave up driving it on the road.

It had a cracked manifold, broken bolt in the exhaust. I fixed all that but have heard it reeks havoc on the o2 sensors. I will unplug the front one see if anything changes.

I am not convinced my injectors are not leaking. I just haven't ordered a set yet.

Did you recalibrate the speedometer?  If you're running stock gears and 42's it could be throwing off the PCM.

[Tr00b]

If you have a skinny looking O2 sensor about the width of a fine sharpie marker... Stock O2 very likely bad. The ecu does not have an out of range fault code for the O2 but probably will derp a code if you unplug it. The jeep just runs like garbage until replaced. Unfortunately there is not an elaborate diagnostic procedure to tell you whether or not the sensor is bad but based on shmptoms you will not be dissapointed. Luckily you did the manifold so it will practically fall out. I removed the old manifold along with the o2 that thing was not going to come out.

[Rio_Grande]

Jeffy that should have read 34 inch, I mistyped it.  My speed sensor is adjusted for 32 inch tires. I may toss them back on today just to take it down the road. These tires are bias ply swampers. I like them off road but they have to be contributing to the wandering issues.

I replaced the 02 sensors years ago and I know I used bostch. Thought they were the best back then. I hear that isint right now.

Tomorrow will tell, I have to drive it at highway speeds for about 30 miles we will see how it goes.

[Rio_Grande]

Did much better today. I think I have to much toe in as it is a touch hard to steer off of straight. And it runs down the road without waiver. No backfiring today but when I got it good and hot there is either something rattling in the converter or muffler.

On the list first though is smaller tires, a track bar and a steering damper.

[chardrc]

My 90 yj would backfire when you drove it hard on road for the first time in a few months. Would always happen when shifting unless you kept slightly on the throttle. I never figured out the cause but it would go away after driving it for a week or so... then again I had TBI so the fuel injection was totally different.